1. Field
Exemplary embodiments of the present invention relate to a non-volatile memory device and a fabrication method thereof, and more particularly, to a non-volatile memory device including a plurality of memory cells that are stacked perpendicularly to a substrate, and a method for fabricating the non-volatile memory device.
2. Description of the Related Art
Non-volatile memory devices retain data although a power supply is cut off. A plurality of types of non-volatile memory devices, such as a NAND flash memory, exist and are used.
As the integration degree of a two-dimensional non-volatile memory device where memory cells are formed in a single layer over a silicon substrate may reach a technical limitation, three-dimensional non-volatile memory devices where a plurality of memory cells are vertically stacked over a silicon substrate may be used. Three-dimensional non-volatile memory devices are divided into vertical channel devices where a plurality of word lines are stacked along channels formed perpendicularly to a substrate and vertical gate devices where a plurality of channel layers are stacked along gates formed perpendicularly to a substrate.
Although two dimensional memory cells use a portion of a substrate as a channel, the three-dimensional non-volatile memory devices do not use a part of a substrate as a channel. Therefore, the three-dimensional non-volatile memory devices cannot perform an erase operation that implants holes into a floating gate of a memory cell through a Fowler-Nordheim Tunneling by applying a high positive voltage to a substrate body having a high-concentration P-type impurity region. Instead, the three-dimensional non-volatile memory devices perform an erase operation by generating Gate-Induced Drain Leakage (GIDL) by applying a high voltage to a gate of a selection transistor and supply hot holes generated from the GIDL current to a channel.
However, since generating many electron-hole pairs may be difficult, the three-dimensional non-volatile memory devices may not efficiently perform an erase operation using GIDL current.